Occurrence, Geographic Distribution, and Antimicrobial Resistance Profiles of Staphylococcus aureus Isolated from Artisanal Fresh Goat Cheese Produced in the Altiplano Potosino Region, Mexico

Abstract

Artisanal fresh goat cheese produced under traditional small-scale conditions may harbor antimicrobial-resistant pathogens. This study assessed the occurrence and geographic distribution of Staphylococcus aureus, characterized antimicrobial resistance, and explored the antibacterial activity of titanium dioxide (TiO2) against multidrug-resistant (MDR) isolates in the Altiplano Potosino region of Mexico. A total of 150 samples from 15 rural communities in seven municipalities were analyzed. Of 38 presumptive isolates, 24 were confirmed as S. aureus (16.0% of samples), occurring only in Charcas and Vanegas. Based on locality-level susceptibility profiles, 9 of 24 confirmed isolates (37.5%) were assigned an MDR phenotype involving macrolides, lincosamides, and aminoglycosides, with clindamycin resistance observed across all five positive localities. In exploratory assays, UV-C-activated TiO2 produced the largest inhibition zones and lowest viable counts. Viable counts were significantly lower under UV-C than under natural sunlight (p = 0.016), but not significantly different from darkness after Bonferroni adjustment (p = 0.073). These findings establish a regional baseline for S. aureus occurrence and antimicrobial resistance and provide preliminary evidence of measurable antibacterial activity of UV-C-activated TiO2 against MDR isolates.